Controlling specific weight of a liquid



Sept. 27, SEBARDT CONTROLLING SPECIFIC WEIGHT OF A LIQUID Filed Jan. 22, 1955 R O T N E V m MLHELML-BFFOZ By (2241* Q E g ATTORNEY United States Patent CONTROLLING SPECIFIC WEIGHT OF A LIQUID Wilhelm Sebardt, Bromma, Sweden, assignor to International Ytong-Stabalite Company Ltd., London, England, a corporation of Great Britain Application January 22, 1953, Serial No. 332,765

Claims priority, application Sweden January 29, 1952 8 Claims. (Cl. 249-14 The present invention relates to an apparatus for automatically controlling the specific weight of a liquid and to the method for providing this automatic control. Such an apparatus is useful in various technical fields where a liquid composed of a plurality of substances is used in which the carrier liquid has a substantially different specific gravity from the substances mixed therewith. Specifically, such an apparatus is useful in the production of concrete containing a mixture of water and cementing components such as slate ashes and lime or quartz sand in finely ground state.

In pouring concrete moulds, it has been the practice to add suflicient concrete to fill the mould to overflowing to insure that the entire mould is completely filled. As a result of this practice and as a result of subsequent leveling-off operations, there is substantial waste of the mixed concrete. This waste should preferably be used in the production of a subsequent concrete mixture. However, in order to avoid a varying concrete mixture it can be seen that a sufficient supply of waste concrete must be kept on hand at all times. Obviously, mixed concrete cannot be stored for any length of time due to the tendency of this material to bind. Due to these difficulties, little success has been attained heretofore in utilizing the waste mixed concrete in making up subsequent concrete mixtures.

It is well known that the tendency of the mixed concrete to bind can be avoided by suspending the concrete in water. Such a slurry has, however, a tendency to leave deposits in a container where it is kept so that deposits form on the sides and bottom of the container. These deposits cause an error in Weighing the added amount of mixed concrete.

The present invention provides an apparatus and method for automatically controlling the weight of a slurry and therefore its consistency.

According to the present invention, the mixed concrete which is the waste from previous moulding operations is brought to the vessel in which the waste slurry is held. There is provided means for weighing the slurry as it leaves this vessel, which means functions to add water to the slurry should the slurry become too heavy. As the slurry becomes lighter with the addition of the water, the weighing means stops the flow of additional water. In addition, there is provided means within the container to properly agitate the slurry to prevent the formation of deposits within the vessel.

One form of the present invention is shown in the attached drawing wherein:

Fig. l is a side elevation of the entire apparatus,

Fig. 2 is a perspective view of the weighing means, and

Fig. 3 is a side elevation of the control means associated with the Weighing means.

Referring now to Fig. 1, there is shown at a suitable conveyor in the form of a belt or chain, running over a pulley or gear 11. This conveyor serves to feed the mixed concrete waste to the container 12. Water is added to the container through a conduit 13 provided with a relay Patented Sept. 27, 1955 controlled valve 14 of a type well-known in the art. Within the container 12 there are provided agitators 15 which are mounted on a shaft 16 suitably journaled in the end walls of the container. There is provided a motor 18 and belt drive 17 to rotate shaft 16. Agitators 15 are so shaped as to serve as scrapers to remove the deposits which may have formed on the bottom and side walls of vessel 12. It can be seen that a vessel 12 should have a cylindrical bottom and side walls with a radius of curvature corresponding to the radius of agitators 15.

Adjacent the bottom of the vessel 12 there is provided a tap for the slurry consisting of a pipe 19 having a pump 20 driven by motor 21 connected therewith. The output conduit 22 from the pump is connected to a flexible coupling 23 which in turn is connected to a U-shaped pipeloop 24 which passes around three sides of the vessel 12. There is connected to the other end of the U-shaped pipe 24 a flexible coupling 25 to which is connected a pipe 26 which is thereafter bent angularly upwards opening above the vessel 12 shown in Fig. 1. It can be seen that the pipe-loop 24 will be filled with the slurry during use of the device and the weight of the volume of slurry passing through the pipe is measured by a means hereinafter described more fully. The pipe-loop 24 is balanced about a shaft 27 which is suitably journaled within the walls of container 12.

The weighing means is shown diagrammatically in Fig. 2 wherein it can be seen that there is provided an arm 28 which is adapted to pivot about a balanced edge 29. Arm 28 carries a counterweight 30 and is provided with a bifurcated end portion cooperating with the electrical contact device 31.

The electrical contact device is shown in detail in Fig. 3. The end portion of the arm 28 is shown at 39 and it can be seen that setting screws 40 and 41 are provided in the end portions. Pivotally mounted on a shaft 42 is an arm 43 which extends between the end portions of the arm 28. Arm 43 is provided with an angularly bent portion 44 having a container 45 mounted on the outer end thereof. Container 45 is shaped as shown and is provided with contacts 46 and 47 on the inner surface thereof. The container is partially filled with mercury so that in one position of the arm 44 the contacts 46 and 47 will be closed. There is further provided as shown in Fig. 1 a clamping device 32 of any suitable variety which serves to damp the oscillations of the U-shaped pipe 24.

The operation of the presently disclosed apparatus is as follows: It will be assumed that so much waste concrete has been added and mixed into the slurry within vessel 12 that the weight of the slurry has increased to its maximum value allowed. The pipe-loop 24 will then, due to the increased weight of the slurry, move downward. Simultaneously, the arm 28 moves upwards and will, during the latter part of its movement, cause movement of the arm 43 until the mercury within container 45 is shifted to a position to close contacts 46 and 47. Contacts 46 and 47 close an electrical circuit 33 to operate a. valve 14 which regulates the amount of water to be added to thin the slurry. By adding the water, the slurry is thinned and as a consequence the pipe-loop 24 is displaced upward until container 45 shifts to the other position whereby the valve 14 is again closed. In this manner the slurry in the container 12 will continuously be kept at a consistency which within a rather small margin will be constant.

For tapping the slurry the following arrangement is made. A branch conduit 34 from pipe 26 ends in a vessel 35. Since the construction of this vessel has no relation to the present invention, it has only been schematically shown. There is provided a valve 36 at the input side of the vessel and a tapping pipe 37 is provided on one side of the vessel so that the opening of pipe 37 is over the edge of vessel 12. It is therefore apparent that when fluid is passing through pipe 34 and vessel 35 it may be returned through pipe 37 to vessel 12. There is shown at 38 a tap-01f valve for the vessel 35.

The slurry will be continuously subjected to activation by means of activators 15 and will be subjected to a continuous weight control by the mechanism associated with pipe-loop 24. The agitators prevent deposits of the slurry within the vessel 12 and assures a homogeneous consistency of the slurry. The control means associated with pipe-loop 24 shows that the homogeneous consistency of the slurry will be the correct consistency. Consequently, it is certain that the slurry tapped 01f from the vessel 35 will always have a correct and homogeneous consistency. The pump 20 also functions as a crusher for any clods which, in spite of the action of agitators 15, may be carried through pipe 19. The continuous circulation of the slurry through the system also assists in maintaining the homogeneous consistency of the slurry. As a matter of fact, in certain forms of the invention, the agitators can be omitted without substantial impairment of the operation of the device.

It should be observed that the quantity of water added through the valve 14 is not measured directly but is only measured insofar as its action in thinning out of the slurry to the correct concentration. The apparatus, therefore, functions equally as well when there is a large quantity of slurry stored within the container as when only a small quantity is present, and it is further apparent that the apparatus operates independently of the purity of the water used. Therefore, it is a further advantage of this invention that as diluting water the slurry-containing surplus water may be used, which water it is otherwise impossible to use.

In certain cases it is not necessary to mount the pipeloop 24 pivotally about the shaft 27 as fully satisfactory results can be obtained by using a fixed pipe loop which can be made subject to bending depending upon the weight of the medium passing through the pipe-loop.

As many apparently widely difierent embodiments of the invention may be made without departing from the spirit thereof, it is to be understood that I do not intend to limit myself to the specific form of the invention as set forth except as indicated in the appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. The method of controlling the weight per unit volume of a fluid medium which includes a relatively heavy substance and a liquid, comprising the steps of continuously circulating the fluid medium through a pipe, v

weighing the fluid medium as it passes through the pipe,

and regulating the amount of liquid added to the fluidmedium to maintain the weight per unit volume of the fluid medium within a desired range.

2. The method of controlling the specific weight of a slurry which includes a mixture of two substances of different specific weights, comprising the steps of continuously circulating the slurry through a U-shaped pivotally supported pipe section, weighing the slurry as it passes through the pipe, closing an electrical circuit when the weight of the slurry exceeds a predetermined value, and adding an additional amount of the lighter susbtance to the slurry when the electrical circuit is closed.

3. The method according to claim 2 including the step of continuously agitating the slurry.

4. An apparatus for controlling the specific weight of a fluid mixture, comprising a container, a pipe loop in communication with the container, means mounting said pipe loop for position response to the weight of fluid mixture passing therethrough, and means associated with said pipe loop and responsive to the position of the same for controlling the amount of liquid added to said fluid mixture.

5. An apparatus as described in claim 4 wherein said pipe loop is U-shaped and is pivotally mounted on a horizontal shaft.

6. An apparatus for controlling the specific weight of a slurry which comprises a liquid and a relatively heavy substance, comprising, in combination, a container, agitating means within said container, an outlet in said container, a pipe loop connected to said outlet, pump means for circulating the slurry through the pipe loop, means pivotally mounting said pipe loop for position response to varying weight in the slurry passing through the pipe loop, means associated with said pipe loop and responsive to the position of the same, and means controlling the addition of liquid to said slurry, said means responsive to the position of the pipe loop actuating said control means whereby the specific weight of the slurry is maintained within a predetermined range,

7. The combination recited in claim 6 wherein said pipe loop is provided with flexible couplings and is pivotally mounted on a horizontal shaft.

8. An apparatus for automatically controlling the specific weight of a slurry containing a mixture of a liquid and a solid relatively heavy substance, comprising a vessel within which the slurry is mixed, an outlet including a pump for discharging the slurry, a pipe loop pivotally supported and extending around the vessel, said pipe loop connected to said outlet by means of a flexible coupling, circuit closing means associated with said pipe loop and responsive to the position of the same, the position of said pipe loop varying according to the weight of the slurry passing therethrough, and valve means for adding the liquid to said slurry mixture, said valve means being controlled by said circuit closing means.

References Cited in the file of this patent UNITED STATES PATENTS 484,078 Wittemann Oct. 11, 1892 1,536,589 Keen May 5, 1925 1,978,558 Van der Horst Oct. 30, 1934 2,072,326 Forster Mar. 2, 1937 2,273,180 De Castro Feb. 17, 1942 

